The RT9801 is a micro-power voltage detector
supervising the power supply voltage level for
microprocessors (µP) or digital systems. It provides
user programmable threshold levels with 0.1V step
ranging from 1.5V to 5V, which covers most digital
applications. It features low supply current of 3µA.
Selection of V
is easily achieved through 3 pins
TH
connected to GND, VDD or floating for different
threshold voltage settings. Two versions of threshold
voltages, 1.5V ~ 4V and 2.5V ~ 5V, which are
programmed in factory are offered by customer
demands.
The RT9801 performs supervisory function by
sending out a reset signal whenever the VDD voltage
falls below a preset threshold level. This reset signal
will last the whole period before VDD recovering.
Reset signal will release after VDD is recovered and
lasts for the whole period of Reset Active Time-out
period.
RT9801 is N-channel, open-drain output and
provided in SOT-26 package.
Ordering Information
Features
z User Programmable Threshold 1.5V to 5V in
0.1V Step with ±3% Accuracy
z Low Supply Current 3µA
z Quick Reset within 20µS
z Built-in Recovery Delay 200mS
z Low Functional Supply Voltage 0.9V
z Small SOT-26 Package
Applications
z Computers
z Controllers
z Intelligent Instruments
z Critical µP and µC Power Monitoring
z Portable/Battery-Powered Equipment
Pin Configurations
Part NumberPin Configurations
RT9801CE
(Plastic SOT-26)
64
5
321
TOP VIEW
1. VSET0
2. GND
3. RESET
4. VDD
5. VSET2
6. VSET1
RT9801
Typical Application Circuit
Package Type
E : SOT-26
Operating temperature range
C: Commercial standard
Reset Threshold
A : 2.5V~5V
B : 1.5V~4V
Marking Information
VDD
µP
GND
RESET
VSET0
GND
RESET
Pull Up
VSET1
RT9801
VSET2
VDD
Part NumberMarking
RT9801ACE1J
RT9 80 1B V
= 2.5V in this example
TH
RT9801BCE1K
DS9801-02 August 2002www.richtek.com
1
RT9801Preliminary
Pin Description
Pin NamePin Function
VSET0Threshold Voltage Selection Pin 1
GNDGround Pin
RESETReset Pulse Output, Negative Pulse
VDDPower Pin
VSET1Threshold Voltage Selection Pin 2
VSET2Threshold Voltage Selection Pin 3
Function Block Diagram
Inter nal Clock
VDD
VSET0
VSET1
VSET2
Threshold Vol tage Se t ting
VSET
CMP
POR
Power On Reset
TIMER
N
RESET
www.richtek.com DS9801-02 August 2002
2
PreliminaryRT9801
Absolute Maximum Ratings
zTerminal Voltage (with Respect to GND)
VDD-0.3V to 6.0V
All Other Inputs-0.3V to VDD+0.3V
z Input Current, VDD20mA
z Continuous Power Dissipation, P
@ TA = 25°C
D
SOT-260.25W
z Operating Junction Temperature Range -40°C ~ 125°C
z Storage Temperature Range-65°C ~ 125°C
z Package Thermal Resistance
SOT-26, θ
zLead Temperature (Soldering, 5sec.)260°C
JA
250°C /W
Electrical Characteristics
(VDD = 3V, unless specified)
ParameterSymbolTest ConditionsMinTypMaxUnits
Operating VDD (V
) RangeV
OUT
Supply Current
Reset Threshold
Threshold Voltage Accuracy
VCC Drop to Reset Delayt
Reset Active Time Out Period
VSET Pin Input Threshold
RESET Output Voltage
I
DD
V
∆V
RD
t
RP
V
V
V
DD
TH
IL
IH
OL
0.9--6V
VDD = 1.5V ~ 3.5V, I
V
= 3.5V ~ 5V, I
DD
TA = 27°C
TA = 27°C
TH
OUT
OUT
= 0
= 0
----3
----3.3
--Note1--V
----3%
Drop = -125mV----20
VDD ≥ 1.02×VTH,
Programmable
TA = 27°C
TA = 27°C
V
< VTH, I
DD
SINK
= 3.5mA
--200--mS
--
--
--0.4--V
0.15V
0.85V
DD
DD
µA
µS
-V
--
DS9801-02 August 2002www.richtek.com
3
RT9801Preliminary
Note 1: Pin Conditions for Programmable Threshold Voltage Setting